<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script>

        var num =+prompt("请输入日期")
        switch (num) {
            case 1 :
                alert("星期一");
                break;
            case  2:
                alert("星期二");
                break;
            case 3 :
                alert("星期三");
                break;
            case 4  :
                alert("星期四");
                break;
            case 5 :
                alert("星期五");
                break;
            case 6:
                alert("星期六");
                break;
            case 7 :
                alert("星期天");
                break;

            default: alert("你输入的日期不对");
        }



    </script>


</head>
<body>

</body>
</html>